Forming and welding tapered tubes



July 1, 1969 J. MORRIS FORMING AND WELDING TAPERED TUBES Sheet Filed June 13, 1966 July 1, 1969 J. MORRIS. 3,452,424

FORMING AND WELDING TAPERED TUBES Filed June 15, 1966 Sheet 3 of 3 J. MORRIS July 1, 1969 FORMING AND WELDING TAPERED TUBES Sheet 3 of3 Filed June 13, 1966 United States Patent 3,452,424 FORMING AND WELDING TAPERED TUBES Jack Morris, Monsey, N.Y., assignor to American Machine & Foundry Company, New York, N.Y., a corporation of New Jersey Filed June 13, 1966, Ser. No. 556,987 Int. Cl. B23k 29/00, 31/02 U.S. Cl. 29-477.7 8 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the manufacture of tapered tubing and more particularly to such tubing which is formed by starting with sheet metal and shaping same to the form of a tapered tube with a longitudinally-extending gap or seam line, which is then welded.

While it is common practice to manufacture sheet metal tubing of uniform diameter by starting with a strip of sheet metal and utilizing forming rolls to shape same into a tubular form on which a longitudinal seam line may then be welded, yet the formation of tapered sheet metal tubing presents a much more difficult problem since, because of the changes in diameter of the tubing along its length, it is impossible in practice to use in the usual way forming rolls of a fixed diameter or radius. So far as is known, no entirely satisfactory way has been devised heretofore for manufacturing such sheet metal tapered tubing uniformily and at the necessary speeds to do so economically and by a continuous roll-forming procedure. Such tubes have a wide variety of possible uses such as for lamp posts and poles for supporting electrical lines as for public utilities, among other uses. Usually it is desirable to be'able to furnish such tubing which, although tapered, will have a circular cross-section, but because of the difference in diameters of the succeeding portions this is diflicult to accomplish, particularly for poles of considerable length.

In accordance with the present invention, these problems are solved by starting with a strip or area of sheet metal of tapered width and which may initially be fiat, although not necessarily so, and by a combination of steps, preferably a succession of steps, forming same into tubing which has more or less flattened side walls of tapering width joined by bottom and top walls which, in cross-section, are curved or arcuate and preferably substantially semi-circular, the welded seam being formed along the mid-portion of one of such portions of curved cross-section. In this way the curved portions, if desired, throughout the length of the tubing may be made with the same curvature and of the same radius if the curvature is semi-circular. Thus the arcuate portions may be formed by suitably rounded surfaces of forming rolls. And the matter of securing the desired taper of the tubing is taken care of by forming the side walls of tapering widths, while the upper and lower wall portions which are of curved cross-section are being formed with uniform curvatures along the length of the tubing. Thereafter, as is often or generally the case, it is desired to have the final tubing of a circular or other cross-section. The tube as shaped in the aforesaid manner may be reshaped on a tapered mandrel to the desired circular or other modified cross-section.

Although the tubing may generally be shaped by using combinations of forming rolls, yet in some cases, especially for thin metal, instead of using forming rolls, the sheet metal may be shaped by the use of dies having suitable curvatures which slidably engage and properly shape the metal as it is drawn past.

Incidentally, it may be mentioned here that terms such as side walls and top and bottom walls, upper and lower etc., are used herein throughout merely in their relative sense as describing the method and equipment in the positions as shown in the accompanying drawings, but it will be understood that the equipment may be oriented to various positions in any desired relation to the horizontal.

The method as above briefly outlined is particularly advantageous when the longitudinal welding seam is to be formed by the use of high frequency heating current. To this end the tubing may be so formed and advanced as to provide a narrow V-shaped gap extending along the desired seam line and with its vertex at a weld point. The high frequency current from a suitable source may be applied by contacts engaging opposite sides of such gap shortly in advance of the weld point so that the current flows along the gap edges from the contacts to and from the weld point in a way heretofore well known per se, for example as disclosed in U.S. Patent to Rudd et al. No. 2,818,488, and with the seam formed by butt welding, lapped welding or so-called mash lap welding. Alternatively the high frequency contacts may be applied at successive points and with the gap either closed or open, as disclosed in U.S. Patent to Rudd et al. No. 2,857,503, or as disclosed in the copending application of Wallace C. Rudd, Ser. No. 544,293, filed April 21, 1966. Also in some cases the high frequency current may be maintained inductively in advance of the weld point by induction coils of suitable known shape, and this possibility is facilitated in that such coils may be mounted in fixed position, since with the method above outlined, the seam line may progress along a fixed plane even though other portions comprising the side walls of the tubing are tapered.

The method and equipment as above outlined for shaping the tubing has a number of significant advantages. First, the same forming rolls may be used for shaping tubing of various different sizes, regardless of the taper, and the same is true as to the rolls used at the welding region. That is, for tubes having different total perimeter-s, the curved cross-sectional portions may be made with the same radius. Furthermore, since the curvature or radius of the edges as formed along the desired seam line remain constant, it is consequently possible to provide a V-gap of constant position and dimensions in advance of the weld point for convenient application of the high frequency current throughout the length of the tubing and independently of the changes in the total perimeter of the finished tubing. At the same time, regardless of the particular welding method used (Whether by high frequency heating, arc welding or other methods, the fact that the tubing has flattened sides during the welding operation, makes it possible to prevent seam rolling during welding. The invention further makes possible forming and welding of tapered tubing in substantially a single operation, thus avoiding separate handling for the forming and subsequent welding operations. Tooling costs for roll forming and costs of dies for many different tapered tube sizes are avoided.

Various further and more specific objects, features and advantages of the invention will appear from the description given below, taken in connection with the accompanying drawings, illustrating by way of example a preferred form of the invention.

In the drawings:

FIG. 1 is a somewhat diagrammatic perspective view illustrating a preferred embodiment of the invention and its operation;

FIG. 2 is a somewhat diagrammatic enlarged illustration of the initial set of forming rolls shown in FIG. 1;

FIG. 3 is a sectional view taken along line 33 of FIG. 2 and simply showing in section a piece of the sheet metal as initially used and which may be tapered along its sides and may be flat, although, as above stated, not necessarily flat;

FIG. 4 is a somewhat schematic enlarged view of the next set of forming rolls appearing in FIG. 1;

FIG. 5 is a sectional view taken substantially along line 55 of FIG. 4 and illustrating the cross-sectional shape of the sheet metal after it has left the first set of forming rolls and is about to enter the second set;

FIG. 6 is a diagrammatic view of the third set of for-ming rolls while FIG. 7 is a sectional view taken substantially along line 77 of FIG. 6 and showing the transverse sectional shape of the metal after it has left the second set of forming rolls and is about to enter between those shown in FIG. 6;

FIG. 8 is a perspective view of a length of the especially-shaped and tapered tubing after it leaves the rolls shown in FIG. 6 and where it will have a cross-sectional shape preferably as shown in FIG. 8a;

FIG. 9 is a diagrammatic view of a roll arrangement which may be used at the welding region;

FIG. 10 is a vertical sectional view of the roll arrangement at the region of welding and at a time when a part of the tapered tubing which has a considerable depth is coming into position for welding;

FIG. 11 is a similar view where a part of the tapered tubing which has a considerably lesser depth is being brought into position for welding;

FIG. 12 is a perspective view of a length of the formed tapered tubing after the seam has been welded thereon;

FIG. 13 is a sectional view taken substantially along line 13-13 of FIG. 12;

FIG. 14 shows a length of the finished tapered tubing after same has been reshaped to circular cross-section as by the use of mandrel means insertable therein in the manner indicated at the right-hand portion of FIG. 1; and

FIG. 15 is a sectional view taken substantially along line 1515 of FIG. 14.

Referring now to FIG. 1 in further detail, a strip or area of sheet metal as initially used, is advanced rapidly past a succession of groups of forming rolls and finally past the welding region by any suitable conveyor or carrying means (not shown) extending along the dashdot line indicated at 21 and preferably along a straight path which initially may be at the level of and in alignment with the longitudinal center line of the strip 20. The travel of the workpiece continues along straight with its mid-portion at this level until the tubing has been shaped to the form shown in FIG. 8. Thereafter preferably the shaped tubing is advanced through the welding region along a straight line which may be in the position shown at 21a in FIG. 1 and at the horizontal level of the desired seam line. That is, substantially up to the region of welding, the workpiece may be advanced with the lower or mid-portion thereof travelling along a uniform level, while the side walls and upper portions of the tubing are being formed to varying heights above that level. But after the tubing has been shaped to the form shown in FIG. 8 and is ready to go through the welding region, same may be advanced along a straight line passing through the desired seam line on the tubing, while the lower portions of the formed tapered tubing extend down at distances below line 21a as the tapered form advances.

Referring now to FIG. 2, the initial two pairs of forming rolls are indicated at 22, 23 and 24, 25. One or both of each of these pairs of rolls may be suitably driven as by motors indicated at 26, 27 in FIG. 1, the rolls being mounted on shafts having suitable journals or supports 28, 29.

The purpose of the rolls 22 to 25 is to shape the tapered side edges of the workpiece 20 to form upstanding flanges 30, 31 (see FIG. 4) these flanges adjoining the main surface of the workpiece preferably along portions of curved cross-section, as indicated at 32, 33, the curvature being substantially that of an arc or a circle, although not necessarily so. It will be noted that these portions are at an angle to the longitudinal center line of strip 20, corresponding to the initial angle of taper of the strip. The peripheral edges of the rolls 22 and 24 are made suitably concave, and the corresponding surfaces of rolls 23 and 25 are suitably convex to establish the curved formations at the bases of flanges 30, 31, as shown in FIG. 4.

Inasmuch as the rolls 22 to 25 inclusive have to engage along edges of the workpiece 20 which diverge from each other as the workpiece advances, the rolls 22, 23 are arranged to rotate along a plane at an angle to the travel line 21 corresponding to the angle of one edge of the workpiece 20, whereas the rolls 24 and 25 rotate along a plane at an angle corresponding to the angle of the opposite edge of the workpiece. And inasmuch as the width across the workpiece between these rolls becomes wider as the workpiece advances, provision is made to retract the rolls correspondingly along with the driving means therefor. This may be accomplished, as schematically indicated in FIG. 1, by mounting the rolls and their driving motors on suitable slidable guide means, as at 35 and 36 respectively. Either suitable mechanical means, or for example fluid-actuated cylinder and piston means 37 and 38 may be provided for gradually retracting the rolls and their mounting means away from the center line of the workpiece to an extent corresponding to the angles of the sides of the workpiece as the latter progresses. The control means for actuating such retracting means at proper speeds and in appropriate timed relation to the advance of the workpiece may, of course, take various forms, either electrical or mechanical.

After the workpiece assumes a shape as shown in FIGS. 4 and 5, same is next passed between a pair of rolls 40, 41, one or both of which may be driven by suitable means (not shown), the lower roll preferably having a central groove 42 of arcuate cross-section (preferably semicircular, although not necessarily so) whereas the periphery of the upper roll 41 has a corresponding convex curved shape, as at 43. Upon passing between these rolls which engage along the center line of the workpiece, the workpiece assumes the cross-sectional shape shown in FIG. 7, Where the portions 30, 31 and 32, 33 remain shaped as before, while the midportion at the bottom assumes a curved cross-sectional shape at 45, corresponding to the peripheral shapes of rolls 40, 41. Preferably this shape is arcuate and with a radius the same as the radius which the portions 32, 33 would have if the edges at 30, 31 were brought together. Here it will be noted that portions 46 and 47, which are to form the sides of the especially-shaped tapered tube, are flat. A perspective view of a portion of the tube as formed at this stage appears at the left-hand portion of FIG. 6 as between a pair ofcylindrical rolls 54 and 55 mounted on preferably substailtially-vertical axes, so that as the work piece emeige's from the'rebetween, it will have the shape shown in FIGS. 8 and 8a, with a longitudinal gap or desired seam line 56 extending along the top edge. 1

Here it will be noted'thatthe upper and lower portions finished tubing of the of the tube may conform substantially in cross-se 1..

to semicircles with uniform and preferably substantially} equal radii throughout the tube length, and the taper is taken care of by reason of the fact that the side wall por-g tions 46 and 47 are of tapered height.

This especially-shaped tubing is now ready to pass through the welding zone. As shown in FIGS. 9, and

11, at or adjacent this zone and at opposite sides thereofl] side wall rolls 60 and 61 may be provided, the lower and mid-portions of which may be substantially cylindrical and the upper portions of which are formed with curvatures corresponding to the curved portions 32, 33 on the upper portion of the tubing. At a location between or close to these rolls, a pair of opposed squeeze rolls 62, 63 may be provided to engage the upper surfaces of the formed tubing at opposite sides of the weld point w or near that point for crowding the heated edges along 2 the gap 56 into welded engagement. That is, the rolls 62v and 63 have peripheries so shaped as to correspond to the curvature of the upper portions 32, 33 respectively of the formed tubing, and to crowd same inwardly and somewhat downwardly into welded engagement along the desired seam line. It should be understood that the rolls 60, 61 and '62, 63, or certain thereof as desired, may be suitably driven by means (not shown) so as to advance the workpiece therebetween.

In order constantly to crowd the whole tubing of tapered height up against the squeeze rolls 62, 63, same may be engaged along the bottom curved portion 45 by a supporting roll 65 rotatably carried as by a yoke 66, which yoke in turn, as indicated in FIG. 9, may be urged constantly upwardly as by cylinder and piston means 67 (FIG. 9). Thus, for example, when the small end of the tapered tube enters the welding region, this lower side will be engaged by the roll 65 at a time when it is thrust to its uppermost position by the pressure cylinder 67 (FIG. 11) and as the tubing advances and portions thereof of greater depth engage the roll 65, such roll will be pushed downwardly to the position shown in FIG. 10 against the pressure of the cylinder means 67, while the tubing will still be held under pressure up in engagement with its upper surfaces at a uniform level as engaged by the rolls 62, 63.

Referring further to FIG. 1, suitable frame means as at 68 may be provided for supporting the roll arrangement 60, 61, 62 and 63, and following such rolls, frame means as at 69 may be provided for supporting any suitable known form of scarfing device for scarfing away any bulging metal formation from along the top of the welded seam 73 so that the external surface of the tubing at the seam will be smooth.

As shown in FIG. 9, high frequency current from a suitable source 70 may be applied by contacts 71, 72 to opposite sides of the gap 56 on the workpiece, so that the current flows therefrom to and from the weld point w and thereby heats the approaching edges of the V-gap to welding temperature upon reaching the weld point. Alternatively, the heating current may be applied or the welding accomplished by other means as outlined hereinabove. The especially-shaped tubing with the Welded seam line at 73 is shown in FIGS. 12 and 13 and at the right hand end of FIG. 1. Then if it is desired to reshape the welded tapered tube to a circular or other cross-section, it may be moved on suitable conveying or supporting means, as at 75, over to the position there shown at 76,

where the smaller end is brought into engagement with a stop and clamping means 77. Then a suitably-shaped mandrel 78, reciprocably operated as by cylinder and piston means 79, may be thrust into the tubing to shape same in accordance with the shape of the mandrel, whereupon the mandrel may be withdrawn leaving the tapered desired shape, usually or preferably circular in cross-section.

Although a certain particular embodiment of the invention is herein disclosed for purposes of explanation, further modifications thereof, after study of this specification, will be apparent to those skilled in the art to which the invention pertains. For example, although the tapered side walls of the tubing as initially especiallyshaped will preferably be flat and interconnected at the top and bottom by generally channel-shaped wall portions of uniform cross-sections or curvatures throughout the length of the tube as formed, yet the side walls may not necessarily be retained flat. Also, while usually the tubing after welding will be reshaped to circular crosssection, same may, of course, readily be shaped to other cross-sections if preferred and depending upon the crosssectional shape of the mandrel used for such reshaping. Reference should accordingly be had to the appended claims in determining the scope of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. Method for forming a tapered sheet metal tube with a longitudinally-extending welded seam which comprises: advancing a strip of the sheet metal which is of longitudinally tapered width, while shaping same to the form of a hollow tube with a longitudinally-extending seam line, such tube being shaped to have a pair of opposed longitudinally-extending side walls of tapered width joined by channel-shaped top and bottom wall portions each respectively of substantially uniform cross section and dimensions along the length of the tube; and then welding the thus-shaped tube along said seam line.

2. Method in accordance with the foregoing claim 1 and in which the side walls as formed with tapered widths are substantially flat.

3. Method in accordance with the foregoing claim 1 and in which the channel-shaped top and bottom wall portions are formed with curvatures which in cross-section are substantially semicircular.

4. Method in accordance with the foregoing claim 1, and in which the sheet metal is shaped to form the hollow tube by a succession of steps comprising: first forming upstanding flange portions of substantially uniform crosssection and dimensions along the sides of the strip of tapered width; then bending the strip along its mid-portions to there form the channel-shaped bottom wall portion also of substantially uniform cross-section and dimensions extending lengthwise of the strip and with the side wall portions extending upwardly and outwardly therefrom; and then forcing said side wall portions toward each other to bring the edges of said flange formations into opposed positions along the desired seam line.

5. Method in accordance with the foregoing claim 1 and in which the tube after welding is forced onto a tapered mandrel of predetermined cross-sectional shape and the tube is thereby reshaped to conform to a corresponding cross-section.

6. Method in accordance with the foregoing claim 1, and in which the tube is shaped to form the seam line along the mid-portion of one of the channel-shaped wall portions and in which the tube is welded along said seam line by causing high frequency current to flow on and to heat the edges of the sheet metal at said seam line to welding temperature upon reaching a weld point.

7. Method in accordance with the foregoing claim 4 and in which pressure is applied at the region of the weld point against the side walls and pressure is also applied at each side of said seam line in directions toward 7' 8 the seam line downwardly to force the edges at the weld 2,857,503 10/1958 Rudd et a1. 21959 point into welded relation. 3,101,401 8/ 1963 Schlotterer 21967 8. Method in accordance with the foregoing claim 1 3,296,852 1/1967 F h 1; 1 72-370 X and in which, during the formation of said hollow tube, 3,329,329 7 19 7 Karmann 22 17 the strip is conveyed along a line which is in alignment 5 3,361,319 1/1963 Sate et a1 2 7 X with the initial median line of the advancing strip, and the 3,361,320 1/1968 Bobmwski formed hollow tube during the welding step being advanced along a line which is in alignment with said beam JQHN CAMPBELL, primary Examine line.

References Cited 10 J. L. CLINE, Assistant Examiner. UNITED STATES PATENTS US. Cl. X.R. 1,534,133 4/1925 Murray 219-59 X 228-47 1,866,256 7/1932 Heineman 219-67 X 

